FIG 2.
Hfq inhibits T3SS gene expression. Wild-type strain PA103 and an hfq mutant carrying an ExsA-dependent PexsD-lacZ transcriptional reporter were transformed with either a vector control (pJN105) or an Hfq expression vector (pHfq). Strains were cultured under noninducing (- EGTA) or inducing (+ EGTA) conditions for T3SS gene expression and assayed for PexsD-lacZ reporter activity. Beta-galactosidase activity is reported in Miller units with the standard error and represents the average of at least three independent experiments. P < 0.01. Cell lysate (Lys) or culture supernatant (Sup) fractions from the same cultures were immunoblotted for ExoU, PcrV, ExsA, and Hfq.